AWUS01 KWNH 131121
FFGMPD
ARZ000-TXZ000-OKZ000-131620-

Mesoscale Precipitation Discussion 0667
NWS Weather Prediction Center College Park MD
720 AM EDT Sun Jul 13 2025

Areas affected...Southeast OK into Southwest AR

Concerning...Heavy rainfall...Flash flooding likely

Valid 131120Z - 131620Z

SUMMARY...Scattered flash flooding remains possible this morning
across portions of southeast Oklahoma and adjacent areas of
southwest Arkansas.

DISCUSSION...Expanding convection to the southeast of a well
defined MCV has increased in coverage and intensity early this
morning. The environmental ingredients in place seem supportive of
this activity persisting into the morning hours. Instability is
marginal (MUCAPE between 500-1000 J/KG), but we do have enough of
an upstream instability pool off to the southwest to likely
sustain this convection. PWs are over 2", and likely have a good
amount of warm rain processes occurring increasing rainfall
efficiency with this activity. Deep layer mean flow is off to the
northeast at ~20 kts, however upwind propagation vectors are
pretty weak and pointed south. This supports some of the southward
backbuilding of convection we have been seeing this morning. The
latest SPC mesoanalysis also depicts a corridor of deep moisture
convergence over this area, with both the 925mb and 850mb moisture
transport axis pointed into the region.

While not necessarily the strongest signal, model guidance does
have some signs of this convective cluster. Both the latest HREF
and REFS have modest 3" neighborhood probabilities, and the 10z
HRRR and 08z RRFS runs now show a better training signal. None of
the guidance show too much more upscale development of the
activity, and by mid to late morning these type of nocturnal
events often tend to weaken. Thus generally expecting the scale of
activity to remain similar over the next few hours, with
backbuilding on the south and southwest flank of the northeast
moving area of convection. Where this backbuilding persists an
isolated to scattered flash flood risk will continue. Hourly
rainfall locally over 2", and total amounts upwards of 3-5" seem
probable in spots. By mid to late morning we should start to see a
bit less organization as low to mid level moisture convergence
should weaken. But we will continue to monitor convective trends.

Chenard

ATTN...WFO...FWD...LZK...OUN...SHV...TSA...

ATTN...RFC...ORN...TUA...NWC...

LAT...LON   35329434 35209395 34689367 34179404 33799488 
            33689571 33609593 33919623 34149642 34469664 
            34599681 34819656 35189587 35259483 

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